From the combined results obtained from the phylogenetic, genomic and chemotaxonomic analyses, it is reasonable to assign strain BDTF-M6T as a member of the genus Pseudoalteromonas (Fig. 1; Figs. S1 & S2; Table 2). Strain BDTF-M6T was distinguished from the type strains of P. caenipelagi, P. rubra, P. byunsanensis and P. amylolyticby differences in several phenotypic characteristics, including nitrate reduction, utilization of some substrates, activity of some enzymes, susceptibility to some antibiotics and DNA G + C contents (Table 1). The distinguished phenotypic properties, 16S rRNA gene sequence similarities and genetic distinctiveness by the ANI and dDDH values suggest that strain BDTF-M6T is separated from other recognized species of the genus Pseudoalteromonas (Chun et al. 2018; Goris et al. 2007; Konstantinidis and Tiedje 2005; Richter and Rosselló-Móra 2009). Based on the polyphasic taxonomic data presented, therefore, strain BDTF-M6T is considered to represent a novel species of the genus Pseudoalteromonas, for which the name Pseudoalteromonas insulae sp. nov. is proposed.
Description of Pseudoalteromonas insulae sp. nov.
Pseudoalteromonas insulae (in’su.lae. L. gen. n. insulae of an island, referring to the source of isolation of the type strain).
Cells are Gram-stain-negative, non-spore-forming, motile by single polar flagellum and ovoid or rod-shaped, approximately 0.2–0.4 µm in diameter and 0.6–10.0 µm in length; a few cells greater than 10 µm in length are observed. Colonies on MA are circular, slightly convex, smooth, glistening, grayish yellow in colour and 2.0–3.0 mm after incubation for 3 days at 25°C. Optimal growth temperature is 25°C; growth occurs at 10 and 40°C, but not at 4 and 45°C. Optimal pH for growth is 7.0-7.5; growth occurs at pH 5.5, but not at pH 5.0. Growth occurs in the presence of 0.5–14.0% (w/v) NaCl with an optimum of approximately 2.0–3.0% (w/v) NaCl. Mg2+ ions are not required for growth. Anaerobic growth does not occur on MA and on MA supplemented with nitrate. Catalase- and oxidase-positive. Nitrate is reduced to nitrite. Aesculin, casein, gelatin, starch, Tween 80 and L-tyrosine are hydrolysed, but hypoxanthine, urea and xanthine are not. L-Aabinose, D-cellobiose, D-fructose, D-galactose, D-glucose, maltose, D-mannose, sucrose, D-trehalose, D-xylose, citrate, formate and succinate are utilized as carbon and energy sources, but acetate, benzoate, L-malate, pyruvate, L-glutamate and salicin are not. In assays with the API ZYM system, activity of alkaline phosphatase, esterase lipase (C8), leucine arylamidase, valine arylamidase, α-chymotrypsin, acid phosphatase and naphthol-AS-BI-phosphohydrolase is present, but activity of other enzymes is absent. The predominant ubiquinone is Q-8. The major fatty acids (> 10% of total fatty acids) are C16:0, summed feature 3 (C16:1 ω7c and/or C16:1 ω6c) and C18:1 ω7c. The major polar lipids are phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid and one unidentified glycolipid.
The type strain, BDTF-M6T (= KACC 22179T = NBRC 115118T), was isolated from a tidal flat sediment collected from Bul island at Ansan on the Yellow Sea, South Korea. The DNA G + C content of the type strain is 50.0% (from genome sequence data). The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence and GenBank accession number for the whole genome shotgun sequence of strain BDTF-M6T are MW364544 and JAGXTQ000000000, respectively.